Call-distributing system.



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C. S. WiNSTON.

CALL DISTRIBUTING SYSTEM.

APPLICAUON HLED Auc.4. 1913.

Patented June 22, 1915.

2 SHiETS-SHEET I.

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CALL DISTREBUTHGG 5%.? 1.

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z/f'zza UNITED STATES r grE T omit;

GHARLES S. WINSTON, OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SWITCHBOARI') AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

CALL-DISTRIBUTING SYSTEM.

Specification of Letters Patent.

Patented June 22. 15915.

To all 1071 0m it may concern lle it known that I, CnAnLns S. \VINSTON, a citizen of the l nited States of America, residing at Chicagmcounty of Cook. and State of Illinois. have invented certain new and useful improvements in (lall Distributing Systems, of which the following is a specification In general my invention relates to calldistributing systems and is directed more particularly to improved selecting means for interconnecting calllnglines and idle operators link circuits.

()ne of the features of my invention is the provision of simple individual line switches which are adapted to operate upon initiation of a call over the associated line toautomatically select an idle cord selector switch preferably of greater capacity, thus giving each telephone line access to a comaratively large number of ope ators link circuits.

For a more complete understanding of my invention reference is to be had to the accompanying drawings in which like reference characters denote like parts and in which- Figure 1 composed of parts 1 and 2, illustrates a call-distribi1ting system embodying my iniention; Fig. 2 illustrates diagrammatically a mechanical line switch adapted .o operate in connection with the line switch circuit B; and Fig. 3 illustrates diagram matieally the preferred contact bank and wiper arrangement. employed in connection with the cord selector switch circuit C.

Referring now more in general to my invention as illustrated, it comprises a sub station A connected by the line conductors L to multiple jacks J and also to'au individual line switch ll at the central ofi'ice, there being one such individual switch B associated with each substation. The switches B each have access to a plurality of cord selectors C.

The cord selectoi; switches C are divided into groups, each group having its bank terminals multiply connected and extended to cord circuits D which are also divided into groups and distributed among the diftereut operators positions. At the right of Fig. 1. part 2, I have illustrated a called substation E connected by the line conductors L to apparatus similar to that connected to the substation A:

In general the system of Fig. '1 operates as follows:. The subscriber at remover; the receiver from the switch-hook which a; starts the individual line switch wi r l and 5 stepping around to select an id curd selector switch (l. As soon as the ii'idiv uai lino switch has sci ed an idle cord s *mr switch (7, the sub ted cord se ector r lill. operates to :,.;p the group wiper (l'l to select an idle group of cord circuits l). utter which the wipers 1-32, 333. 34 are stepped to select an idle cord circuit in the group. Upon selection of the col-d circuit. a a ing,- lamp L is lighted sin! ding; the (per The operator hrows the lislciiiin and. assuming that it is substation l1 thus she inserts the plug; I into the la k a" connecting the calling substi'ition ..h the wanted line. After the conver ation been inns-di d the subsci' res respective recon ers to the :uriteli-lmoh ing' the two supervisory lamps l1 and. L

in the cord circuit. the operator discoimecting he plug: from its jack. The cord C and the individual line switch stored to normal and are now availa' use in esta lii-hing' other connections.

Before proceeding with a new anon-s description of Fig. 1. I will relcr to 1-- seleotor mechanism (7 illu trated in Fig oi the cord which preirra ly etnploy For use with the selector and c re. circuits of the system of Fine. 1 .n switch sucl as is shown in an upplf o'l William Kaisling For automalic suil'cl for telephone systems, Serial No. noodles. filed January 3rd, 1911. may l e used.

The switch referred to in the previous paragraph. in gen ral comprises a bunt; oi" contacts made up of 100 sets of contacts with three contacts 36. 37, to each set, and di ided into ten groups of ten contact sets each as illustrated diagranimaticall v in l lg. 3. A set of wipers 32. 33. 34-, are provided, to coi peratc with the bank contacts, a primary magnet (corresponding to PM of the switch circuits) being adapted to primarily adiust the wipers through the medium of a primary shaft PS to select a group of contacts. and a secondary magnet (corresponding to SM of the switch c r cuits) is provided to step the wipers ones-d, the medium of a secondary shaft F in a secondary direction in a plane at right angles to the primary. to select a contact set of the selected group. The swi ch Killa pair of so- 'inr; opposing rcsmcti. ely.

up ol contacts 3% 37, provided and a adaptrd to engage said For each primary step ii; mil unccs wiper T' from one ci'urtart to the nor-t one. this mm'cmcni. also carrying wipers 3'2, 33. 54, alongi'rzr-n Xu}; .o row -lg'ftcr the primary 'zucu. to solar a row or group of can 3 3%., arc rotate-2d by a orv ari mincut to select. a contactof a selected group.

To rrlcaso the wipers, that is. to restore them to n rmal. the secondary magnet is in rt l op the wipers in a sec uni the last contact of 1 may are automatically )5 by the sprin fa rcfcrrcd a diricrcni: path. than that i: alvai-ica mzrv'cuuirnt o:

i a com- 7. atcd by 3. Thus, the on .jwirch the contact ends of mar-y lili'ifcilflfl to 2 than in a second .c in 9 ml in the release of {he wipcrs i ti't-H-f. l the c how 5, the last ili y are au ocor-tact in he or mp. cl marically relcasml to rontin. c their rest/rm,

continucd mo'cinenioclcl to the primary more opp air. d rrctmn until thcy reach a po. alum". the sta ting pointwh-sn l'zcy an. mowdownwardiv through a p ane paraliol to the sccrmdary movement. ii -t in a direction o giiposiie to the secondary l'uoicmcni; until. they reach their normal starting mint.

A seif of primary ofl normnl spring con tacts PQN are moved upon the first primary stop of the switch while a set of sscondan oil-normal spring contacts SON are moved upon the first secondary step of the switch.

Fig. 2 illustrates diagrammaticallya switch mechanism adapted to operate in connection with circuit B, like reference characters denoting like parts. This switch comprises sets of bank contacts 6, 7, 8, prefi crably ten, and cooperating wipers 3, 4, and 5 which are mounted upon a central shaft carryin a ratchet wheel 62 adapted to be driven the motor magnet MM. It. will 66 be noted that two check pawls 63 and 64 are employed, pawl 63 being normally in on gagcmcnt with ratchet 62 while pawl 64 is normally out of cngagemcnt with said ratchet. in the operation of Fig. 2, in accordance with circuit B. upon the initiation tion to corn ii. this in a piano par? .il '1 of a call by the removal of the receiver from the switch hook, linc relay LR is energized thus causing the associated pawl 64 to engage ratchet Wheel. 62 and thereafter the cutoff rclay (Y) energized causing its associated pawl 63 to disengage the ratchet whccl F32. Thor [tor the motor magnet MM advances the wipers over the contacts followed by the dccncrgization of CO, but Lil is maintained cucrgizcd so that both pau'ls c3 and 64 are engaging ratchet wheel 6 To rclwsc lhc switch B, line relay LR is dciincrf thus withdrawing pawl 6s from cngigcumnt with ratchet 62 and thereafter cur-oll' relay CO is again energized moving pawl out of engagement with ratchet 62 allowing the wipers to be restored by a suitable spring. On the first stop off normal. contacts 0N assume their alternate position and are maintained so until the wipers 1 .mtacts ()N mal position.

Referring now more in detail to the apl 'WiTfltUS employed in illustrating my inven lion. it comprises a. well-known type of substation A connected by the line 1 c0mprisconductors l and 2 to an individual line s itch P5. and multiple jacks at the switch board at the ccntral ollice. The said individual line switch B comprises a line relay LR energized upon initiation of a call, a cut-oil relay CO operated upon encrgization of relay LR. and the motor magnet MM which steps the wipers 3, 4, and 5 to select an idle cord selector switch G. Oil normal contacts ON arc provided and they assume thcir alternate position on the first stop of ihe wipcrs 3, 4. and The lines and line switches ii .ins'v on grouped in any dcsirare restored whereby said are again moved to their norable man: er a n l preferably arrange them in groups of 100 with ten associated cord sclcctors C. I preferably use two-dimension 106 point. cord selector switches, having ten groups of ten contact sets multiply connected to cord circuits D. The cord selcctors are adapted to test the cords by groups and thcn individually to sclcct an idle cord in a selected group.

The cord selector C comprises a release relay RR which is energized when an individual line switch B picks out an idle cord selector with which HR is associated. The primary relay PR is energized by the operation of RR, thus closing a circuit for primary magnet PM which stops the group test wiper GT .in a. primary direction to select an idle group of cord circuits. A secondary rclay SR is also provided which upon oncrgization, opcrates a secondary magnet SM to step the wipers 32, 33, and 34 in a secondary direction to select an idle cord circuit in the selected group. Primary oflnormal contacts FUN and secondary olfnormal contacts SON are provided, the primary Off-l10flntl contacts PON assuming their alternate position upon the first primary step of the switch and the secondary off-hormal contacts SON assume their alternate position upon the first secondary step of the r-. ipors.

Now referring to the cord circuit D it comprises a group busy relay GER, one of these relays being associated with each cord circuit and having a series ground extending hi-(nigh its normally open contacts it! to ground atnormally open ground 50 of the group busy relay of another cord circuit. So long as all of the relays GER of a group are energized this ground connection from alternate contact 50" associated with them I a reaches the associated group contacts 55, rendering the group non-selectable by a group test wiper GT. As long as one group relay associated with the ten cord circuits is de'onergized the series ground will be interrupted and the group contact will remain selectable. An answering supervisory relay AS pr villi-ll and when energized by a sub station calling. Clikfl'tS its alternate contacts to light the calling lamp L to notify the operator at D that a substation is calling. A calling supervisory relay CS is also provided and is ener izcd when the called subscriher hangs up to light the supervisory lamp 1 to notify the operator at l l that the convex-satin 's finished. A test relay TB. is provided which operates in 50 .swith the cut-oil a, C of the individual switch ll. A li. ning key'LK is provided and a ringing lacy BK, a ringing generator RG and the calling plug P. A busy key BK also provided and when said key is thrown to the right all the cord circuits of the corre sponding group beyond this circuit will be made busy, and when the key is thrown to the left the particular cord circuit will be made busy without r-il'ecting in any Way the remaining cord circuits of the same group.

()peratZ0n.--Assiuning now that, the sub-- scriber at substt-iti 'ui wishes to ciiinvcr o 1th the subscriber at substation l), the sub scribor at A lr iiunir his receiver from the su'itt-lrluioli', this aei cau ing the enurgiza' tion of the line relay lill over a circuit traced from lia'll 'n' through. th wiuiliug of relay Lil. wiper ii. f im-tor normal con tact of cut ill relay (ll), cornlurtor Q, lhrough the substation A. conductor l, normal contact ll of ("Jlkoll relay (ft). a contact 7 to ground. lpon the encrgi of relayldl :lil out" izing circuit for the cut-oil relay (it is Ha'olisl from batte y through the winding of cutoli' relay (it the normal coi'itact of ofi'morinal contacts UN, to ground at alternate contact 11 of relay Lil, energizing the cut-oil relay h'el (T) l'llt'll'Pl llll-t closes its alternate Contact which establishes an energizing circuit For 'H' magnet MM traced from un grounded pole of alternating current enerator G through the motor magnet M alternate contacts 12, 13, to ground. The motor magnet MM energizes ste ping the wipers 3, l. and around and ii the first contacts are busy the motor magnet coninues to step the wipers around until an ungroundcd test contact (3 is encountered. l pon the first step of the Wipers, the oilnornial switch ON assumes its alternate position ()Pfllllllg the energizing circuit for cut oil relay CO but assuming that the first contactis busy, another circuit for relay CO is established from battery through the winding of (it), alternate contact 14, conductor 15, alternate contacts 16, 17 of relay LR, conductor 18, wiper 3, contact 6, com ductor 19 to ground at an alternate contact of primary OifJIOIIHZl contacts PON of another cord selector associated with the busy contact. When the private wiper 3 finds an ungroundcd contact, relay Q0 dee'nergizes interrupting the circuit of the motor magnet MM and rendering the wipers 3, 4 and inert.

When the individual line switch has selected an idle cord selector C, the release relay RR of the selected cord selector is energized from battery through the winding of relay ll R. conduct r '20, normal Contact 21 of the test relay T, conductor 8, contacts la, wiper conductor S, normal Contact 9, relay (0. conductor 2, through the substa lion. conductor 1, normal contact of relay conductor "ll, wiper 4, contact 7, con- (luctin' T to ground at normal contact Upon energization of relay RH a circuit for the primary relay PR is established traced from battery through the winding of PR, alternate contact 23 of HR to ground at nor- 1113] contact 24 of the primary oft-normal contacts POX. The encrgization of relay lll closes a circuit for the primary magnet PM which may be traced from the unfl'i')lll'l(ll(l pole f the generator G through the winding? oi magnetv PM, alternate contact iii to ground. The energizations of the primary magnet l step the ground le t wiper (I'l to select an idle group of cord circuits. l pou the first step of wiper il, the primary oll norinal contacts FUN assume their alternate position interrupting tho initial unorggixin g circuit oi the relay R. lust assuming the first contacts encoun tonal are busy, another energizing circuit for the relay lll established from but tori. through the winding of relay PR. its

alternate contact ill. conductor 27, to ground at other group contacts that are busy over which u'ri'iup test wiper passes in selecting an idle group of rural c r uits.

As won as the emu;- tust. wiper GT finds an iniuroiiiulril contact. the mergizing: circuit for the relay PR interrupted, ileenergizingit, the said drhnru'gination of re lay PR opening the circuit of primary magnet PM arresting the movement of the wiper GT. Also, upon the de'energization of the relay PR an energizing circuit for the secondary relay SR is established traced from battery through the winding of SR, conductor 28, alternate contact 29 of PON, normal contact 30 of the se 'ondary off-normal contacts SON to ground at normal contact 25. Upon the energization of relay SR a circuit for the closed, traced from the ungrounded pole of the generator (i through the winding of magnet SM to ground at alternate contact 31. Upon the energization of magnet SM the wipers 32, 33, 34 are stepped up to select an idle cord circuit. Upon the first step of the wipers 32, 33, 34, the secondary offnormal contacts SON assume their alternate positions interrupting the initial energizing circuit of the relay SR but assuming the first contact encountered is busy, another circuit is established from battery through the relay SR, conductor 28, alternate contacts 39, 40 conductor 41 to grounded contacts 36 over which the wiper 32 passes, thus the wipers 32, 33. 34 are stepped until private wiper 32 finds an ungrounded contact which opens the circuit for the secondary relay SR arresting further secondary movement of the wipers 32. 33, 34. Upon the decnergization of relay SR an energizing circuit for the relay T is established from battery through the winding of the relay T. alternate contact 42, conductor 43 to ground at normal contact 31, contacts 22 and 21 assuming their alternate positions and establishing the continuity of the talking conductors to the selected cord circuit D.

Upon extension of the calling line to the idle cord I). an energizing circuit for the answering siuu-rvisory relay AS is stablished from battery through the right hand winding of the relay AS, conductor 8*, contacts 3R. wiper ill, alternate contact 21, conductor S, contacts 8, wiper 5, normal contact 1), conductor 2, conductor 1, normal con- (act 10 conduttor T, wiper 4, contacts 7, conductor T alternate contact 22, wiper 33, contacts 37, conductor T to ground through the left hand winding of the relay AS, energizing the relay AS. Upon energization of AS, its contacts assume their alternate positions closing a circuit for the group busy relay (1BR traced from battery through the winding of GBR alternate contact 49 to ground, energizing the relay GBR and making the particular cord circuit busy putting a ground on the private contact, said ground being extended to said contact from alternate contact 4-9 of AS through alternate contact 48 of (illlt, conductor 47, to said private contact. (Also upon energization of relay AS its alternate contact 44 is closed lighting the supervisory or calling lamp L,

secondary magnet SM is calling line to cord I).

the circuit of which may be traced from battery through the lamp L, alternate contact 41 to ground at normal contact 45.) Relay upon its said cnergization opens the cir cuit for relay RR but the relay RR being slow to release holds its armature attracted until another circuit is established for it which may be traced from battery through the relay RR, conductor 20, alternate contact 46, normal contact 40, conductor 41, wiper 32, contacts 36, conductor 47, alternate contact 48 of the group busy relay (lBh to ground at alternate contact 49 of the answering supervisory relay AS. The relay GBR, it will be remembered was energized upon the energization of the relay AS. which occurred upon extension of the The operator at O observing the signal L throws the listening key LK to ascertain the wants of the subscriber at substation A. Assuming now that the substation E is wanted, the operator tests the called line as to its idle the tip of the plug P against the sleeve of the jack J and if the line is busy the sleeve of the jack J is atditl'erent potential than the plug ti and the operator receives the usual click in her head receiver.

Assuming that the line L is idle, there is no testing difference in potential and the operator at 0 receiving no busy click inserts the plug P into the jack J This operation closes an energizing circuit for the test relay TR of the cord circuit and the cut-off relay (0 of the individual switch B with which the called line is associated. This may be traced from battery through the cutoff relay CO, conductor 51, normal contact ()N, the ring contacts of the jack J and the plug P, conductor 52, the winding of the test relay TR to round. This energizes the relays TR and (J0 Upon the energization of the relay TR, contact 45 assumes its alternate position, removing the ground from the supervisory lam L, efi'acing said lamp, and also closing flCHCllit for the calling 'supervisory lamp L, this circuit being traced from battery through the lamp L normal contact 53, alternate contact Arfifto ground lighting the said la n L it re mal'ning lighted until the cal ed-for subscriber at substation E answers. The operator now throws her ringing key RK connecting ringing current from the ungrounded pole of generator RG, through the uliper alternate contact of the ringing key R the tip contacts jack J conductor 1, the call bell and condenser of the substation E, conductor 2 the ring contacts of the jack J and the plug P to ground at the lower alternate contact'of the ringing key RK. When the called sub scriber answers, the calling supervisory reof the plug P and or busy condition by placing lay CS is energized which circuit is traced 1 0 from battery through the right hand winding of the relay CS, conductor S to the sleeve contacts of the plug P and jackJ, conductor 2, through the substation, cona doctor 1 tip contacts of-the jack J, and plug l, muuluctor T alternate contact 5-1, through the left hand winding of relay. CS to ground. energizing the relay CS. Upon energimlion. its contact is interrupted, the circuit of the lamp L and it, notifying the operator that a respoi'rc has been secured from thecalled substation.

ii( ;lc(z.ve.--'llie subscribers at substations 1:; A and E having finished conversation, re-

place their receivers upon their respective s\"tchi .ool s opening the energizing circults of the relays AS and CS. The relay Ab; deiinergizing, closes an energizing cir- Ir'or the lamp L from battery through i lamp L, normal contact 44 to ground at alternate contact 45 lighting the lamp. L. 'l'hc relay CS denergizing, closes an enegizing circuit for the lamp L from bat- Za iery through the lamp L, normal contact 53 to ground at alternate contact to, lighting the lamp L. The operator observing the two lights knows that the subscribers have replaced their receivers and removes the i P from the jack J. This opens the "llt deiinergizcs and contact 45 asits normal position ellacing the lamps if and L. Contact 57 assumes its norm. ition opening the circuits of the will of the 'cord circuit and relay of the cord SQlQf'tUi. The relay ER decloses an energizing circuit for t lt which is traced from battery paid. relay Ell. conductor 28, alterr t; .ts .3). 3 conductor 60 to ground at normal contact .61. l pon the energizat ou of relay SR, an energizing circuit is rloa i t r the secondary n'iagnet Sill. being from the uugroumlcd pole oigentrawl orcitor (2 to ground. at alternate contact 31,1. 'lhr ensni operation of the second- -t HM steps the vripcrshZ. 33,34 in directi n beyond the last con- .ur: group, from which position the ill be restored to normal by spring described. When the relay SR it opens the circuit of the relay tact 3L opening the talking courluctors alt contacts 46 and 21 of relay T luring oration. Primary nit-normal N now assume their normal po- 5 won, opening the alternate contact 29 and oting the circuit of SR. Relay, 9R opening the circuit of QM renmid magnet inert. The secondary o ual m litants 30E of ci'uurse also normal position when the wiper thus placing all of the appacircuit ot relays TR and 00 The ratus of the cord selector at normal and renderiit available for other connections.

Following the restoration of the cord selector switch C, switch B is restored this being brought about by the interruption of alternate contact 2% of P0)? of switch C, thus causing the deeuergization of the line relay LR which was held up through said alternate contact of PON. Upon restoration of LR, its normal contact 11 is closed establishing an energizing circuit for CO which is traced from battery through CO alternate contact of ON to ground at normal contact 11 of LB. Thereby CO attracts its armature, withdrawing the check pawl 63 from engagement with the ratchet on the shaft of switch B, and LR is deenergized the pawl 62 associated therewith is withdrawn from the ratchet. the wipers 3, 4 and 5 thereby restoring to normal. Upon restorat on ofthe wipers, ON assumes its normal position opening the energizing circuit of CO restoring it and now the switch being normal the line of substation A is available for use in establishing other connections.

I have preferably arranged my invention so that the subscriber at the calling substation has control of the restoration of the apparatus used in extending a call to an operators link circuit up to the time of the operator answering the call. by connecting her listening key in circuit. That is, my system is so arranged that should a calling subscriber replace his receiver upon its switch-hook prior to the time the operator connects the associated listening key across the selected cord circuit, the apparatus will be restored and the calling lamp L ellaceil. After the listening key TJI has been connected, or While the plug P is in connection with a called line. the restoration of the an paratus is controlled by the operator.

Assuming that a call has been extended from substation A to cord circuit D in a manner as previously described, and before the operator has connected the listening key LK in circuit the subscriber at A replaces his receiver upon its switch-hook. This in' terrupts the circuit for answering supervisory relay AS which deiinergizes inter rupting the locking contacts 49 and allowing the restoration of relay GBR and RR to effect the restoration oi the switches C and B. Of course after the operator has con nected the listening key LK, or While the plug P is inserted into the jack J of a called line, a locking ground from LK or alternate contact 57 of TR is ell'ective to hold relays GBR and RR independent of the ground from alternate contact 49 ot' With the above arrangement the ilC-Cltltlilf tal winking of a switch-hook although it may extend a connection, allows for the re lease of such connection and therefore does not permit the tying up of the operators cord circuits by false calls Or, a suhscribcr after removing his receiver and exteridin a call may decide no connection is Wante and if the receiver is replaced before the operator answers, the lamp L is ell'aced and the apparatus restored.

While I have referred to a particular type of cord selector, and one which is of the so called two-dimension type, it is to be understood that other forms of cord selectors may be used. Neither doI desire to be limited to the particular line switch shown as other forms of such switches may be used. For the above reasons I do not desire to be lin1- ited to the exact structure as shown and described but aim to cover all such changes and modifications as come within the spirit and scope of the appended claims.

What I claim as new and desire to secure by United States Letters Patent is:

1. A call distributing system comprising telephone lines, automatic line switches for said lines, cord selectors multiply connected to terminals of said line switches, operators cord circuits, and means controllable over a calling line for causing its line switch to test its terminals progressively to automatically select an idle cord selector and said cord selector to thereafter automatically select an idle cord.

2. A call distributingsystem comprising telephone lines, one-dimension automatic line switches for said lines, two-dimension cord selectors multiply connected to terminals of said line switches, operators cord circuits, means controllable over a calling line for causing its line switch to automatically select an idle cord selector, and means whereby said cord selector thereafter automatically selects an idle cord.

3. A call distributing system comprising telephone lines, one-dimension automatic line switches for said lines, two-dimension cord selectors accessible by said line switches, operators cord circuits accessible by said cord selectors, means controllable over a calling line for causing its line switch to automatically select an idle cord selector, and means whereby said cord selector thereafter automatically selects an idle cord.

4. A call distributing system comprising telephone lines, one-dimension automatic line switches for said lines, two-dimensioh cord selectors having terminals divided into groups, operators cord circuits connected to said terminals, means controllable over a calling line for causing its line switch to automatically select an idle cord selector, and means whereby said cord selector thereafter tests said terminals by groups and individually to select an idle one of said cord circuits.

5. A call distributing system comprising telephone lines, one-dimension automatic line switches for said lines, twodimension cord selectors multiply connected to term nals of said line switch and having terini nals divided into groups. operators cord circuits multiply connected to aid sel c or terminals, means controllable over a c line for causing its line switch is iilitullu cally select an idle cord selector, and means whereby said cord selector tiienzafter tests said terminals by groups and individually to select an idle one of said cord circuits,

6. A telephone system comprising telephone lines, operators cord circuits distributcd among operators positions for extending the circuits of said lines. individual selectors for said lines, cord selectors accessi ble from the line switches, and means responsive to initiation of a call over an of said lines to cause progressive operation of line and cord selectors snore vely to connect a calling line through s d, operating selectors to the first idle cord ci cuit.

7. A. telephone system comprising telephone lines, operators cord circuits dis tributed among operators positions for ex tending the circuits of said lines. individual progressive selectors for said lines, progressive cord selectors accessible from the line switches and having access to cord circuits oi a plurality of operators positions. and means responsive toinitiation of a call over any of said lines to cause progressive operation of line and cord selectors successively to connect a calling line through said operating selectors to the first idle cord circuit.

8. A telephone system comprising a group of telephone lines, operators cord circuits distributed among operators positions for extending the circuits of said lines, individual progressive selectors for said lines, cord selectors multiply connected to the ter niinals of the line switches, said cuits being: multiply connected to terminals of the cord selectors. and means responsive to initiation of a call over any of said lines to cause progressive operation of line and cord selectors to connect a calling line through said operating selectors o an idle cord circuit. a

9. A telephone system comprising telephone lines, operators cord ciruiits distributed among operators positions {or extending the circuits of said lines, individual progressive selectors for said lines, cord selectors multiply connected to the terminals of the line switches, said cord selectors having groups of terminals to which the cord circuits are multiply connected, and means responsive to initiation of a call over any of said lines to cause operation of a line switch to select an idle cord Selector and operation of said cord selector to select an cord cir-.

sponsive to initiation of a call over any of said lines to cause progressive operation of hue and cord selectors "from a zero or normal position successive-1y to connect a call-' ing line through said operating selectors to the first idle cord circuit.

11. A telephone system comprising telephone lines, operators cord circuits distributed among operators positions for extending the circuits of said lines, progressively operable forwardly selecting switches for interconnecting calling lines and the i.

cord circuits, and means responsive to initiation of a call over any of said lines to cause progressive operation of a plurality of said selectors successively for connecting the calling line to an idle cord circuit.

Signed by me at Chicago, county of Cook and State of Illinois, in the presence of two witnesses.

- CHARLES S. \VINSTON. Witnesses G. E. MUELLER, M. R. Rocnronn. 

